Mobile station, base station, communication system, and communication method

ABSTRACT

When a scrambler ( 54 ) performs IQ multiplexing of output signals from a spreader  52  and a distributor  53  in order to generate a complex signal (I signal and Q signal), amplitude coefficients βcc(I) and βcc(Q) are determined in accordance with signal powers on I axis and Q axis.

TECHNICAL FIELD

[0001] The present invention relates to a mobile station, a basestation, a communication system, and a communication method which arecapable of performing data communication with high speed.

BACKGROUND ART

[0002] The ITU (International Telecommunication Union) has adoptedplural wireless communication methods called the 3^(rd) generation asIMT-2000 for mobile wireless communication method typically used in thefield of cellular phones. In Japan W-CDMA (Wideband Code DivisionMultiple Access) method as one of them is commercially available from2001.

[0003] W-CDMA is made to obtain a communication speed of the maximum 2Mbps (bit per second) per mobile station. The 3GPP (3^(rd) GenerationPartnership Project) as one of standardization groups has determined thespecification of the first edition as Release 99 version (Release 1999)which was summarized at 1999.

[0004]FIG. 1 is a general schematic diagram of a conventionalcommunication system. In FIG. 1, reference number 1 designates a basestation, and 2 denotes a mobile station performing a wirelesscommunication with the base station 1. Reference number 3 indicates adownlink for use in data transmission from the base station 1 to themobile station 2, and 4 indicates an uplink for use in data transmissionfrom the mobile station 2 to the base station 1.

[0005]FIG. 2 is a diagram showing an internal configuration of themobile station 2. In FIG. 2, reference number 11 designates adistributor for distributing data DPDCH of a dedicated data channel(Dedicated Physical Data Channel) in parallel and outputting obtaineddata DPDCH1-DPDCH6 of plural data channels. Reference number 12 denotesa spreader for performing a spread spectrum process for dataDPDCH1-DPDCH6 output from the distributor 11 and control data DPCCH of acontrol channel (Dedicated Physical Control Channel). The spreader 12multiplies the data DPDCH1-DPDCH6 and the control data DPCCH byspreading codes for channel separation.

[0006] Reference number 13 indicates a scrambler for generating acomplex signal (I signal: In phase signal, Q signal: Quadrature signal)by performing IQ multiplexing for output signals from the spreader 12.Reference number 14 denotes a modulator for generating a modulatedsignal by performing orthogonal modulation of a complex signal (I signaland Q signal) generated at the scrambler 13. Reference number 15indicates a frequency converter for converting in frequency themodulated signal generated at the modulator 14 to a radio frequencysignal. Reference number 16 designates an antenna for transmitting theradio frequency signal output from the frequency converter 15.

[0007]FIG. 3 is a diagram showing an internal configuration of thespreader 12 and the scrambler 13. In FIG. 13, reference numbers 21 to 26indicate multipliers for multiplying the data DPDCH1-DPDCH6 output fromthe distributor 11 by spreading codes Cd,1 to Cd,6 for use in channelseparation. Reference numbers 27 designates a multiplier for multiplyingthe control data DPCCH of the control channel by a spreading code Cc foruse in channel separation. Reference number 31 to 36 denote multipliersfor multiplying the output signals from the multipliers 21 to 26 by anamplitude coefficient βd for the data DPDCH. Reference number 37designates a multiplier for multiplying the output signal from themultiplier 27 by an amplitude coefficient βc for the control data DPCCH.

[0008] Reference number 38 denotes an adder for adding the outputsignals from the multipliers 31 to 33, and 39 denotes an adder foradding the output signals from the multipliers 34 to 37,

[0009] Reference number 40 denotes a multiplier for multiplying theoutput signal from the adder 39 by imaginary number “j”, 41 indicatesadder for adding the output signals from the adder 38 and the multiplier40. Reference number 42 designates a multiplier for multiplying theoutput signal from the adder 41 by an identification code Sdpch,n for acellular station in order to generate the complex signal (I signal and Qsignal), and then outputting the generated complex signal.

[0010] Next, a description will be given of the operation of theconventional communication system in which data are transmitted from themobile station 2 to the base station 1.

[0011] When transmitting data to the base station 1, as shown in FIG. 1,the mobile station 2 uses the uplink 4 for the transmission data. InW-CDMA standard, when using the uplink 4, the mobile station 2 can usemaximum six channels for the transmission data according to acommunication speed required in communication service.

[0012] In the following explanation, data on six data channels andcontrol data for one control channel are transmitted for briefexplanation.

[0013] First, the distributor 11 in the mobile station 2 distributes thedata DPDCH of the dedicated data channel in parallel and outputs thedata DPDCH1-DPDCH6 for the plural data channels.

[0014] When the distributor 11 outputs the data DPDCH1-DPDCH6 for theplural data channels, the multipliers 21-26 in the spreader 12 multiplythese data DPDCH1-DPDCH6 with the spreading codes Cd,1-Cd,6 for channelseparation. The multiplier 27 in the spreader 12 multiplies the controldata DPCCH for the control channel by the spreading code Cc for channelseparation.

[0015] The scrambler 13 performs IQ multiplexing for the output signalfrom the spreader 12 in order to generate the complex signal (I signaland Q signal).

[0016] That is, the multipliers 31-36 in the scrambler 13 multiply theoutput signals from the multipliers 21-26 in the spreader 12 by theamplitude coefficient βd. The multiplier 37 in the scrambler 13multiplies the output signal from the multiplier 27 by the amplitudecoefficient βc for the control data DPCCH.

[0017]FIG. 4 is a diagram showing a table of possible values of theamplitude coefficients βc and βd.

[0018] The amplitude coefficients βd and βc are coefficients for use inthe determination of a power ratio between the data DPDCH1-DPDCH6 andthe control data DPCCH, which have been defined inTS25.213v3.6.0(2001-06) Release 1999 in 3GPP standard. Right side inthis table shows the possible values of the amplitude coefficients βcand βd.

[0019] The adder 38 in the scrambler 13 adds the output signals from themultipliers 31-33 and the adder 39 in the scrambler 13 adds the outputsignals from the multipliers 34-37.

[0020] The multiplier 40 in the scrambler 13 multiplies the outputsignal from the adder 39 by imaginary number “j” so as to assign theoutput signal from the adder 39 to Q axis.

[0021] The data DPDCH1, DPDCH3, and DPDCH5 are assigned on I axis andthe data DPDCH2, DPDCH4, and DPDCH6 are assigned on Q axis. TS25.213 in3GPP standard defines how to assign data channels on I axis/Q axis.

[0022] Next, the adder 41 in the scrambler 13 adds the output signalsfrom the adder 38 and the multiplier 40. The multiplier 42 in thescrambler 13 multiplies the output signal from the adder 41 by anidentification code Sdpch,n to be used to identify a dedicated mobilestation, and then outputs the complex signal (I signal and Q signal).

[0023] When the scrambler 13 generates the complex signal (I signal andQ signal) in such a manner described above, the modulator 14 performsthe orthogonal modulation for the complex signal (I signal and Q signal)so as to generate the modulated signal.

[0024] When the modulator 14 generates the modulated signal, thefrequency converter 15 converts this modulated signal in frequency,generates the radio frequency signal, and amplifies and outputs thegenerated one to the antenna 16. Through the antenna 16 the radiofrequency signal is transmitted to the base station 1.

[0025] When receiving the radio frequency signal transmitted from themobile station 2, the base station 1 performs inverse processes to theprocesses in the mobile station 1 in order to obtain the necessary data.

[0026] The above conventional case has explained the case to set the sixdata channels. When the set number of the data channels is not more than5, no process for unnecessary data channel is performed because the dataare assigned on I axis and Q axis in the order of increasing datanumber, for example, the data DPDCH1 is firstly assigned and the dataDPDCH2 is then assigned. The set number of the data channels isdetermined based on the communication service and the communicationspeed.

[0027]FIG. 5 is a diagram showing a complex plane of only one datachannel.

[0028] In this case, the data DPDCH1 for the data channel is assigned onI axis and the control data DPCCH for the control channel is assigned onQ axis. Because the data DPDCH1 and the control data DPCCH areorthogonal to each other, the base station 1 can separate the receiveddata in channel and then demodulate the separated data.

[0029] It is possible to perform the same operation for the case wherethe set number of the data channels is 2, 3, 4, 5, or 6. In this case,the channel component in the same axis can be separated using thespreading code for channel separation.

[0030] The above conventional example has described the case to set thedownlinks 3 and the uplink 4 between the base station 1 and the mobilestation 2. In order to achieve a further high speed data communicationin the downlink from the base station 1 to the mobile station 2, HSDPA(High Speed Downlink Packet Access) has been proposed and examined (seeTR25.858 v1.0.0 (2001-06) “High Speed Downlink Packet Access: PhysicalLayer Aspects (Release 5)”.

[0031]FIG. 6 shows HSDPA in which a new downlink 5 is added in additionto the downlink 3 in the conventional case.

[0032] In the addition of the new downlink 5, it has been examined thatthe mobile station 2 transmits a response data (ACK/NACK) and the liketo the high speed packet data in the downlink to the base station 1.However, as shown in FIG. 6 in which the response data (ACK/NACK) istransmitted through the exclusive control channel (as the uplink channel6). Through the exclusive control channel the response data areseparated and identified using the spreading code for channelseparation, like the same manner for the conventional control channel,and then added and multiplexed in the conventional uplink 4. TR25.858defines to describe “additional DPCCH” as the exclusive control channel.

[0033] Because the conventional communication system has theconfiguration described above, it is necessary to assign the additionalexclusive control channel on I axis and Q axis. This causes a drawbackwhere a distortion is generated at the built-in orthogonal modulator (ororthogonal modulator and amplifier) in the modulator 14 in the mobilestation 2 because nonlinear section of input/output characteristic mustbe used, when the peak power of I axis or Q axis is increased byassigning the exclusive control channel to I axis or Q axis, forexample.

[0034] When the balance between the signal powers of I axis and Q axisis decayed, the peak power of the modulated signal output from themodulator 14 after the orthogonal modulation is greater than the peakpower of the modulated signal of the case where the signal powers of Iaxis and Q axis are in balance. For example, in case an amplifierincorporated in the frequency converter 15 in the mobile station 2amplifies the radio frequency signal, a distortion occurs because theamplifier uses in amplification a non-linear part of the input/outputcharacteristic thereof. When the non-linear component in the distortiongenerated in the amplifier is output, this non-linear component and thesignal component of the frequency band adjacent to this linear componentinterfere to each other. The reception of the adjacent frequency band isthereby disturbed by jamming.

[0035] The present invention is made to overcome the above drawbacks. Itis an object of the present invention is to provide a mobile station, abase station, a communication system, and a communication method whichare capable of suppressing the generation of a distortion in amplifiersand thereby to suppress the occurrence of jamming in the adjacentfrequency band.

DISCLOSURE OF INVENTION

[0036] In carrying out the invention and according to one aspectthereof, there is provided a mobile station capable of generating acomplex signal by distributing control data of an additional controlchannel on I axis and Q axis, and performing IQ multiplexing for them inthe case of adding control data of an additional control channel.

[0037] It is thereby possible to suppress the generation of a distortionin an amplifier and thereby to suppress the occurrence of jamming in theadjacent frequency band.

[0038] The mobile station according to the present invention distributesthe control data for the additional control channel on I axis and Q axisin consideration of a signal power of I axis and a signal power of Qaxis in the case of adding control data of an additional controlchannel.

[0039] It is thereby possible to suppress the generation of a distortionin the amplifier and thereby to suppress the occurrence of jamming inthe adjacent frequency band.

[0040] The mobile station according to the present invention distributesthe control data for the additional control channel on I axis and Q axisso that the signal power of I axis becomes equal to that of Q axis inthe case of adding control data of an additional control channel.

[0041] It is thereby possible to suppress the generation of a distortionin the amplifier efficiently.

[0042] The mobile station according to the present invention assigns thecontrol data for the additional control channel to one axis whose signalpower is smaller than that of the other axis in I axis and Q axis in thecase of adding control data of an additional control channel.

[0043] It is thereby possible to suppress the generation of a distortionin the amplifier with a simple configuration.

[0044] The mobile station according to the present invention assigns thecontrol data for the additional control channel on Q axis when thenumber of data channels is an odd number, and assigns the control dataon Q axis when it is an even number, in the case of adding control dataof an additional control channel.

[0045] It is thereby possible to suppress the generation of a distortionin the amplifier with a simple configuration.

[0046] The mobile station according to the present invention assigns thecontrol data for the additional control channel on Q axis in the case ofadding control data of an additional control channel.

[0047] It is thereby possible to suppress the generation of a distortionin the amplifier and to have a circuit with a simple configuration.

[0048] A base station according to the present invention synthesizescontrol data for an additional control channel distributed on I axis andQ axis and outputs the synthesized one, when the control data for theadditional control channel are distributed on I axis and Q axis.

[0049] It is thereby possible to suppress the generation of a distortionin the amplifier and to suppress the occurrence of jamming in theadjacent frequency band.

[0050] A communication system according to the present invention, in thecase of adding control data of an additional control channel, IQmultiplexing means distributes the control data for the additionalcontrol channel on I axis and Q axis, performs IQ multiplexing, andoutputs a complex signal. Further, IQ separation means in a base stationsynthesizes the control data for the additional control channeldistributed on I axis and Q axis and outputs the synthesized one whenthe control data for the additional control channel are distributed on Iaxis and Q axis.

[0051] It is thereby possible to suppress the generation of a distortionin the amplifier and thereby to suppress the occurrence of jamming inthe adjacent frequency band.

[0052] A communication method according to the present invention has thefollowing steps in a case to add the control data for the additionalcontrol channel. In a mobile station, control data for an additionalcontrol channel are distributed on I axis and Q axis, IQ multiplexing isperformed in order to generate a complex signal. In abase station, thecontrol data distributed on I axis and Q axis are synthesized and outputwhen the control data for the additional control channel are distributedon I axis and Q axis.

[0053] It is thereby possible to suppress the generation of a distortionin the amplifier and thereby to suppress the occurrence of jamming inthe adjacent frequency band.

[0054] Other objects, features and advantages of the present inventionwill become apparent in the following description and appended drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0055]FIG. 1 is a schematic diagram of a conventional communicationsystem;

[0056]FIG. 2 is a diagram showing an internal configuration of a mobilestation;

[0057]FIG. 3 is a diagram showing an internal configuration of aspreader and a scrambler;

[0058]FIG. 4 is diagram showing a table of possible values of theamplitude coefficients βc and βd;

[0059]FIG. 5 is a diagram showing a complex plane in case of one datachannel;

[0060]FIG. 6 is a schematic diagram showing a conventional communicationsystem;

[0061]FIG. 7 is a diagram showing a configuration of a mobile stationapplicable to a communication system according to a first embodiment ofthe present invention;

[0062]FIG. 8 is a diagram showing a configuration of a base stationapplicable to a communication system according to the first embodimentof the present invention;

[0063]FIG. 9 is a diagram showing an internal configuration of aspreader, a distributor, and a scrambler;

[0064]FIG. 10 is a diagram showing an internal configuration of adescrambler, a despreader, and a synthesizer;

[0065]FIG. 11 is a flowchart showing a communication method according toa first embodiment of the present invention;

[0066]FIG. 12 is a diagram showing a complex plane in case of one datachannel;

[0067]FIG. 13 is a diagram showing a configuration of a mobile stationapplicable to a communication system according to a second embodiment ofthe present invention;

[0068]FIG. 14 is a diagram showing a configuration of a base stationapplicable to a communication system according to the second embodimentof the present invention;

[0069]FIG. 15 is a diagram showing a complex plane in case of one datachannel;

[0070]FIG. 16 is a diagram showing a complex plane in case of two datachannels;

[0071]FIG. 17 is a diagram showing a configuration of a mobile stationapplicable to a communication system according to a third embodiment ofthe present invention;

[0072]FIG. 18 is a diagram showing a configuration of a base stationapplicable to a communication system according to the third embodimentof the present invention;

[0073]FIG. 19 is a diagram showing a complex plane in case of one datachannel;

[0074]FIG. 20 is a diagram showing a complex plane in case of two datachannels;

[0075]FIG. 21 is a diagram showing CCDF characteristic of a modulatedwaveform;

[0076]FIG. 22 is a diagram showing CCDF characteristic of a modulatedwaveform;

[0077]FIG. 23 is a diagram showing CCDF characteristic of a modulatedwaveform;

[0078]FIG. 24 is a diagram showing CCDF characteristic of a modulatedwaveform;

[0079]FIG. 25 is a diagram showing CCDF characteristic of a modulatedwaveform; and

[0080]FIG. 26 is a diagram showing CCDF characteristic of a modulatedwaveform.

BEST MODE FOR CARRYING OUT THE INVENTION

[0081] The best mode for carrying out the invention will now bedescribed in detail with reference to the accompanying drawings.

FIRST EMBODIMENT

[0082]FIG. 7 is a diagram showing a configuration of a mobile stationapplicable to a communication system according to a first embodiment ofthe present invention. In FIG. 7, reference number 51 designates adistributor for distributing data DPDCH in parallel and the outputtingthe distributed data DPDCH1-DPDCH6 in plural data channels. Referencenumber 52 denotes a spreader for performing a spread spectrum processesfor the data DPDCH1-DPDCH6 output from the distributor 51 and controldata DPCCH and ADPCCH (additional DPCCH) of control channels bymultiplying those data DPDCH1-DPDCH6, and control data DPCCH and ADPCCHby spreading codes for use in channel separation.

[0083] Reference number 53 indicates a distributor for distributing thecontrol data ADPCCH after the spread spectrum process performed by thespreader 52.

[0084] Reference number 54 indicates a scrambler for generating acomplex signal (I signal and Q signal) by performing IQ multiplexing forthe output signals from the spreader 52 and the distributor 53.

[0085] The IQ multiplexing means consists of the distributor 51, thespreader 52, the distributor 53, and the scrambler 54.

[0086] Reference number 55 denotes a modulator for generating amodulated signal by performing orthogonal modulation of the complexsignal (I signal and Q signal) generated at the scrambler 54. Referencenumber 56 indicates a frequency converter for converting in frequencythe modulated signal generated at the modulator 55 to a radio frequencysignal. Reference number 57 designates an antenna for transmitting theradio frequency signal output from the frequency converter 56.

[0087] The transmitting means consists of the modulator 55, thefrequency converter 56, and the antenna 57.

[0088]FIG. 8 is a diagram showing a configuration of a base stationapplicable to the communication system according to the first embodimentof the present invention. In FIG. 8, reference number 61 designates anantenna for receiving the radio frequency signal transmitted from themobile station 2, and 62 denotes a frequency converter for converting infrequency the radio frequency signal received through the antenna 61 toa base band signal and outputting the obtained base band signal.Reference number 63 indicates an orthogonal demodulator for performingorthogonal demodulation for the base band signal transmitted from thefrequency converter 62 and outputting a complex signal (I signal and Qsignal).

[0089] The receiving means consists of the antenna 61, the frequencyconverter 62, and the orthogonal demodulator 63.

[0090] Reference number 64 designates a descrambler for multiplying thecomplex signal (I signal and Q signal) transmitted from the orthogonaldemodulator 63 by an identification code to identify the mobile station2 from other mobile stations. Reference number 65 indicates a despreaderfor multiplying the output signal from the descrambler 64 by a spreadingcode for use in channel separation in order to separate data of eachchannel. Reference number 66 designates a data channel synthesizer forsynthesizing the data DPDCH1-DPDCH6 for the data channels in order toreconstruct the data DPDCH of the dedicated data channel. Referencenumber 67 indicates a synthesizer for synthesizing the control dataADPCCH for the control channel distributed on I axis and Q axis.

[0091] The IQ separation means consists of the descrambler 64, thedespreader 65, the data channel synthesizer 66, and the synthesizer 67.

[0092]FIG. 9 is a diagram showing an internal configuration of thespreader 52, the distributor 53, and the scrambler 54. In FIG. 9,reference numbers 71 to 76 designate multipliers for multiplying thedata DPDCH1-DPDCH6 output from the distributor 51 by spreading codesCd,1 to Cd,6 for use in channel separation. Reference number 77 denotesa multiplier for multiplying the control data DPCCH for the controlchannel by the spreading code Cc for use in channel separation.Reference number 78 designates a multiplier for multiplying control dataADPCCH for an additional control channel to be newly added by aspreading code Ccc for use in channel separation. Reference numbers 81to 86 denote multipliers for multiplying the output signals from themultipliers 71 to 76 by an amplitude coefficient βd for the data DPDCH,87 indicates a multiplier for multiplying the output signal from themultiplier 77 by an amplitude coefficient βc for the data DPCCH, and 88and 89 designate multipliers for multiplying the output signal from thedistributor 53 by the amplitude coefficient βcc for use in the controldata ADPCCH.

[0093] Reference number 90 designates an adder for adding the outputsignals from the multipliers 81-83 and 88. Reference number 91designates an adder for adding the output signals from the multipliers84-87 and 89.

[0094] Reference number 92 designates a multiplier for multiplying theoutput signal from the adder 91 by imaginary number “j”, 93 denotes anadder for adding the output signal from the adder 90 and the outputsignal from the multiplier 92 together.

[0095] Reference number 94 indicates a multiplier for multiplying theoutput signal from the adder 93 by an identification code Sdpch,n toidentify one mobile station from others, and then outputting thegenerated complex signal (I signal, Q signal).

[0096]FIG. 10 is a diagram showing an internal configuration of thedescrambler 64, the despreader 65, and the synthesizer 67. In FIG. 10,reference number 100 designates multipliers for multiplying the complexsignal (I signal and Q signal) output from the descrambler 64 by theidentification code Sdpch,n. Reference numbers 101-104 denotemultipliers for multiplying the I signal output from the descrambler 64by each spreading code Cd,1, Cd,3, Cd,5, and Ccc for use in channelseparation.

[0097] Reference numbers 105-109 indicate multipliers for multiplyingthe Q signal output from the descrambler 64 by each of spreading codesCd,2, Cd,4, Cd,6, Cc, and Ccc for use in channel separation. Referencenumber 110-118 designate integrators for integrating in time the outputsignals from the multipliers 101-119 along the time length of thespreading code.

[0098]FIG. 11 is a flowchart showing a communication method according tothe first embodiment of the present invention.

[0099] Next, a description will be given of the operation to transmitdata from the mobile station 2 to the base station 1, where the datainclude the data of six data channels and the control data of twocontrol channels, for brief explanation.

[0100] First, the distributor 51 in the mobile station 2 distributes thedata DPDCH for the dedicated data channel in parallel, and outputs thedata DPDCH1-DPDCH6 for plural data channels (Step ST1).

[0101] When the distributor 51 outputs the data DPDCH1-DPDCH6 for theplural data channels, the spreader 52 performs the spread spectrum bymultiplying the data DPDCH1-DPDCH6 for the plural data channels and thecontrol data DPCCH and ADPCCH for the control data channels by spreadingcodes (Step ST2).

[0102] That is, the multipliers 71-76 in the spreader 52 multiply thedata DPDCH1-DPDCH6 for the plural data channels output from thedistributor 51 by the spreading codes Cd,1-Cd,6 for use in channelseparation.

[0103] The multiplier 77 in the spreader 52 multiplies the control dataDPCCH for the control channel by the spreading code Cc for use inchannel separation. The multiplier 78 in the spreader 52 multiplies thecontrol data ADPCCH for the additional control channel to be newly addedby the spreading code Ccc for use in channel separation.

[0104] The distributor 53 distributes the output data from themultiplier 78 to the multipliers 88 and 89 in the scrambler 54 after themultiplier 78 in the spreader 52 multiplies the control data ADPCCH forthe additional control channel by the spreading code Ccc for use inchannel separation (Step ST3).

[0105] The distribution ratio for the multipliers 88 and 89 performed bythe scrambler 54 is 1:1 in this example. However, it is possible todetermine another distribution ratio based on signal powers of I axisand Q axis.

[0106] The scrambler 54 performs IQ multiplexing of the output signal inorder to generate the complex signal (I signal and Q signal) (Step ST4).

[0107] That is, the multipliers 81-86 in the scrambler 54 multiply theoutput signals from the multipliers 71-76 by the amplitude coefficientβd for the data DPDCH. The multiplier 87 in the scrambler 54 multipliesthe output signal from the multiplier 77 by the amplitude coefficient βcfor the data DPCCH.

[0108] The multiplier 88 in the scrambler 54 multiplies the outputsignal from the distributor 53 by the amplitude coefficient βcc(I) forthe data ADPCCH. The multiplier 89 in the scrambler 54 multiplies theoutput signal from the distributor 53 by the amplitude coefficientβcc(Q) for the data ADPCCH.

[0109] By the way, the amplitude coefficients βcc(I) and βcc(Q) for thecontrol data ADPCCH are determined in accordance with the signal powersof I axis and Q axis. That is, they are determined so that the signalpower of I signal becomes equal to the signal power of the Q signal,both the signal powers will be output from the scrambler 54.

[0110] In this example, FIG. 12 shows the complex plane of one datachannel. For example, when the signal power of the data DPDCH1 is “1.5”and the signal power of the control data DPCCH is “1.0”, the amplitudecoefficients βcc(I) and βcc(Q) are determined so that the signal powerof the control data ADPCCH (I) in I axis becomes “1.0” and the signalpower of the control data ADPCCH(Q) in Q axis becomes “0.5”.

[0111] Next, the adder 90 in the scrambler 54 adds the output signalsfrom the multipliers 81-83 and 88 together, and the adder 91 in thescrambler 54 adds the output signals from the multipliers 84-87 and 89together.

[0112] The multiplier 92 in the scrambler 54 multiplies the outputsignal from the adder 91 by imaginary number “j” in order to assign theoutput signal from the adder 91 on Q axis.

[0113] Next, the adder 93 in the scrambler 54 adds the output signalsfrom the adder 90 and the multiplier 92, and the multiplier 94 in thescrambler 54 multiplies the output signal from the adder 93 by theidentification code Sdpch,n in order to output the complex signal (Isignal and Q signal).

[0114] When receiving the complex signal (I signal and Q signal) fromthe scrambler 54, the modulator 55 performs orthogonal modulation forthe received complex signal (I signal and Q signal) in order to generatethe modulated signal. (Step ST5)

[0115] When the modulator 55 generates the modulated signal, thefrequency converter 56 converts in frequency the modulated signal to theradio frequency signal, and outputs the converted one to the antenna 57(Step ST6). Through the antenna 57 the radio frequency signal istransmitted to the base station 1.

[0116] When receiving the radio frequency signal transmitted from themobile station 2 through the antenna 61, the frequency converter 62 inthe base station 1 converts in frequency the received one in order togenerate the base band signal (Step ST7).

[0117] When receiving the base band signal from the frequency converter62, the orthogonal demodulator 63 performs orthogonal demodulating forthe base band signal in order to generate the complex signal (I signaland Q signal) (Step ST8).

[0118] When receiving the complex signal (I signal and Q signal) fromthe orthogonal demodulator 63, the descrambler 64 multiplies thereceived complex signal (I signal and Q signal) by the identificationcode in order to distinguish the target mobile station from otherstations (Step ST 9). That is, the multiplier 100 in the descrambler 64multiplies the complex signal (I signal and Q signal) output from theorthogonal demodulator 63 by the identification code Sdpch,n for themobile station identification.

[0119] The despreader 65 multiplies the output signal from thedescrambler 64 by the spreading code for channel separation in order toseparate the data of each channel (Step ST10). That is, the multipliers101-104 in the despreader 65 multiply the I signal output from thedescrambler 64 by the spreading codes Cd,1, Cd,3, Cd,5, and Ccc. Themultipliers 105-109 in the despreader 65 multiply the Q signal outputfrom the descrambler 64 by the spreading codes Cd,2, Cd,4, Cd,6, Cc, andCcc for channel separation.

[0120] The integrators 110-118 in the despreader 65 integrate the outputsignals from the multipliers 101-109 along the spreading code timelength in order to reconstruct the data DPDCH1-DPDCH6 for the datachannels and the control data DPCCH for the control channel.

[0121] The data channel synthesizer 66 synthesizes the dataDPDCH1-DPDCH6 for the data channels in order to reconstruct the dataDPDCH for the dedicated data channel (Step ST11).

[0122] The adder 67 adds the output signals from the integrators 113 and118 in the despreader 65, so that the control data ADPCCH for theadditional control channel to be newly added can be reconstructed (StepST12).

[0123] As has been apparently understood by the above description,according to the first embodiment, when the scrambler 54 performs IQmultiplexing of the output signals of the spreader 52 and thedistributor 53 in order to generate the complex signal (I signal and Qsignal), the amplitude coefficients βcc(I) and βcc(Q) for the dataADPCCH are determined in accordance with the signal powers of I axis andQ axis. It is thereby possible to suppress a distortion caused in theamplifier in the frequency converter 56, so that the occurrence ofjamming in the adjacent frequency band can be suppressed.

[0124] The first embodiment has designed to allocate the six datachannels. The present invention is not limited by this case, when theallocated number of data channels is not more than five, the data DPDCH1is firstly assigned on I axis/Q axis and the remained data are thenassigned on I axis/Q axis in order. That is, no process for unnecessarydata channel is performed. The allocated number of the data channels isdetermined based on necessary communication service such as acommunication speed.

SECOND EMBODIMENT

[0125]FIG. 13 is a diagram showing a configuration of a mobile stationapplicable to a communication system according to a second embodiment ofthe present invention. FIG. 14 is a diagram showing a configuration of abase station which is applicable to the communication system accordingto the second embodiment of the present invention. In those FIGS. 13 and14, the same components of the first embodiment shown in FIGS. 7 and 8will be referred with the same reference numbers and the explanation ofthem is omitted here.

[0126] Reference number 58 designates a selector (IQ multiplexing means)for outputting the control data ADPCCH for the control channel afterspread spectrum to one of the multipliers 88 and 89 in the scrambler 54.Reference number 68 designates a selector (IQ separation means) forinputting and then outputting the control data ADPCCH for the controlchannel transferred from one of the integrators 113 and 118 in thedescrambler 64.

[0127] The first embodiment has previously described the case in whichthe distributor 53 distributes the output signals from the multiplier 78in the spreader 52 to the multipliers 88 and 89 in the scrambler 54, andthe multipliers 88 and 89 in the scrambler 54 multiply the output signalfrom the distributor 53 by the amplitude coefficients βcc(I) and βcc(Q)so that the signal power of I signal becomes equal to the signal powerof Q signal. In the second embodiment it is possible that the selector58 outputs the output signal of the multiplier 78 in the spreader 52 tothe multipliers 88 or 89 in the scrambler 54 in consideration of thesignal powers of I axis and Q axis in order to assign the control dataADPCCH for the control channel to one axis of a smaller signal power inI axis and Q axis.

[0128] That is, TS25.213 as 3GPP standard has defined that data of datachannel are assigned on I axis when the set number of data channels isone (see FIG. 15), and data for each data channel are assigned on I axisand Q axis when two (see FIG. 16). That is, the data of the datachannels are assigned on I axis and Q axis, alternately.

[0129] In the second embodiment, in order to keep the balance of thesignal power of I axis and the signal power of Q axis, the selector 58in the mobile station 2 outputs the output data of the multiplier 78 tothe multiplier 89 in the scrambler 54 when the set number of the datachannels is an odd number so that the control data ADPCCH of the controlchannel are assigned on Q axis.

[0130] In order to obtain the control data ADPCCH of the control channelassigned on Q axis, the selector 68 in the base station 1 inputs thecontrol data ADPCCH of the control channel transferred from theintegrator 118 in the descrambler 64 and outputs the control dataADPCCH.

[0131] On the other hand, the selector 58 in the mobile station 2outputs the output data of the multiplier 78 in the spreader 52 to themultiplier 88 in the scrambler 54 when the set number of the datachannels is an even number so that the control data ADPCCH of thecontrol channel are assigned on I axis.

[0132] In order to obtain the control data ADPCCH of the control channelassigned on I axis, the selector 68 in the base station 1 inputs thecontrol data ADPCCH of the control channel transferred from theintegrator 113 in the descrambler 64 and outputs the control dataADPCCH.

[0133] As described above, according to the second embodiment, like theeffect of the first embodiment, it is possible to suppress thegeneration of a distortion in the amplifier in the frequency converter56 and thereby possible to suppress the occurrence of jamming in theadjacent frequency band, for example.

[0134] The above second embodiment has descried the case where the axison which the control data of the control channel are assigned isdetermined based on the set number of the data channels. The presentinvention is not limited by this case, for example, it is possible thatthe selector 58 in the mobile station 2 determines the axis on which thecontrol data ADPCCH of the control channel are assigned based on themeasured signal powers of I axis and Q axis.

THIRD EMBODIMENT

[0135] The second embodiment has shown the case in which the controldata ADPCCH of the control channel are assigned on one axis of a smallersignal power in I axis and Q axis. Like the third embodiment, it ispossible to assign the control data ADPCCH of the control channel onlyon Q axis, as shown in FIG. 19 and FIG. 20.

[0136] That is, it can be considered that a spreading code length of thecontrol data ADPCCH of the control channel is approximately 256 which isalmost equal to the length of the control data DPCCH of the controlchannel.

[0137] Accordingly, the signal power of the control data ADPCCH of thecontrol channel is smaller than the signal power of the data DPDCH1 andthe like of the data channel. Further, in the Internet use, because itcan be considered that the amount of data transferred on uplink issmaller than that on downlink, the set number of data channels becomesone in many cases where a link for HSDPA is allocated.

[0138] Here, FIG. 21 to FIG. 26 are diagrams showing simulation examplesof CCDF (Complimentary Cumulative Distribution Function) characteristicof an output waveform from the scrambler 54 when the control data ADPCCHof the control channel are assigned on I axis or Q axis in various setnumber of the data channels (using “N” in those figures).

[0139] In FIG. 21 to FIG. 26, reference character “I” designates theCCDF characteristic when the control data ADPCCH are assigned on I axis,and reference character “Q” denotes the CCDF characteristic when thecontrol data ADPCCH are assigned on Q axis.

[0140] The CCDF characteristic shows the ratio (percentage %) that amomentary power is in time over an average power. The CCDFcharacteristic is more shifted right, the above ratio becomes greater(having a large fluctuation in power). That is, it means that the ratioto take the momentary power of a larger value when compared with theaverage power becomes large. For example, when the set number of thedata channels is one (N=1) and the control data ADPCCH of the controlchannel are assigned on Q axis, the time ratio to take the momentarypower approximately greater by 3.5 dB of the average power becomes 0.1percentage (%).

[0141] In general, a distortion often occurs in the amplifier when asignal of a larger fluctuation is input. In order to avoid theoccurrence of a distortion, it is required to have the linearity in alarge power section. This causes to increase the current consumption.

[0142] As can be understood from FIG. 21, when N=1 (only one datachannel DPDCH1), the characteristic is greatly changed according to theuse of I axis or Q axis. In this case, the occurrence to generate thedistortion is smaller when the control data ADPCCH are assigned on Qaxis.

[0143] Similarly, the axis to which the data are assigned is switchedaccording to the set number N. It can be understood that the data areassigned on Q axis when N is an odd number, and the data are assigned onI axis when N is an even number, so that the CCDF characteristic becomesgood. These results are equal to the results of the second embodiment.

[0144] This means that the above assign method is the most effectivemethod to reduce the distortion from the view point of the CCDFcharacteristic.

[0145] It can be understood that when compared with the case of N=1, thecase of N>1 takes a small distortion because the difference of thesignal powers between I axis and Q axis is not large.

[0146] Accordingly, from the view point to keep the balance between thesignal powers on I axis and Q axis and the view point of thecharacteristic of the input signal of the amplifier, there is no problemin practical use even if the control data ADPCCH of the control channelare assigned on Q axis together with the control data DPCCH of thecontrol channel.

[0147] Thus, when the control data ADPCCH of the control channel arealways assigned on Q axis, it is possible to eliminate the distributor53, the synthesizer 67, or selectors 58 and 68, as shown in FIG. 17 andFIG. 18. This can achieve the effect to reduce the configuration andsize of the circuit in the mobile station, the base station, and thecommunication system.

INDUSTRIAL APPLICABILITY

[0148] As described above, the mobile station, the base station, thecommunication system, and the communication method according to thepresent invention are particularly suitable for high speed datacommunication to transmit and receive a complex signal in IQmultiplexing.

What is claimed is:
 1. A mobile station comprising: IQ multiplexingmeans for performing IQ multiplexing of transmission data for datachannel and control data for control channel, and generating a complexsignal; and transmission means for modulating the complex signalgenerated at the IQ multiplexing means, and transmitting the modulatedone, wherein in the case of adding control data of an additional controlchannel, the IQ multiplexing means distributes the control data for theadditional control channel on I axis and Q axis in IQ multiplexing inorder to generate a complex signal.
 2. The mobile station according toclaim 1, wherein in the case of adding control data of an additionalcontrol channel, the IQ multiplexing means distributes the control datafor the additional control channel on I axis and Q axis in considerationof a signal power of I axis and a signal power of Q axis.
 3. The mobilestation according to claim 1, wherein in the case of adding control dataof an additional control channel, the IQ multiplexing means distributesthe control data for the additional control channel on I axis and Q axisso that a signal power of I axis becomes equal to a signal power of Qaxis.
 4. The mobile station according to claim 1, wherein in the case ofadding control data of an additional control channel, the IQmultiplexing means assigns the control data for the additional controlchannel to one axis whose signal power is smaller that that of the otheraxis in I axis and Q axis.
 5. The mobile station according to claim 1,wherein in the case of adding control data of an additional controlchannel, the IQ multiplexing means assigns the control data for theadditional control data to Q axis when the number of the data channelsis an odd number, and assigns it to I axis when it is an even number. 6.The mobile station according to claim 1, wherein in the case of addingcontrol data of an additional control channel, the IQ multiplexing meansassigns the control data for the additional control channel to Q axis.7. A base station comprising: receiving means for receiving a radiofrequency signal transmitted from a mobile station, demodulating theradio frequency signal in order to output a complex signal; IQseparation means for performing IQ separation for the complex signaloutput from the receiving means, and outputting transmission data for adata channel, control data for a control channel, and control data foran additional control channel, wherein when the control data for theadditional control channel are distributed on I axis and Q axis, the IQseparation means synthesizes the control data for the additional controlchannel distributed in I axis and Q axis and outputs the synthesizedone.
 8. A communication system comprising: a mobile station comprising:IQ multiplexing means for performing IQ multiplexing of transmissiondata for a data channel and control data for a control channel, andgenerating a complex signal; and transmission means for modulating thecomplex signal generated at the IQ multiplexing means, and transmittingthe modulated one, and a base station comprising: receiving means forreceiving the signal transmitted from the mobile station, demodulatingthe received signal in order to output the complex signal; and IQseparation means for performing IQ separation for the complex signaloutput from the receiving means, and outputting the transmission datafor the data channel and the control data for the control channel,wherein in the case of adding control data of an additional controlchannel, the IQ multiplexing means in the mobile station distributescontrol data for an additional control channel on I axis and Q axis, andperforms the IQ multiplexing in order to generate the complex signal,and when the control data for the additional control channel aredistributed on I axis and Q axis, the IQ separation means in the basestation synthesizes the control data for the additional control channeldistributed on I axis and Q axis and outputs the synthesized one.
 9. Acommunication method comprising the steps of: in a mobile station,performing IQ multiplexing of transmission data for a data channel andcontrol data for a control channel in order to generate a complexsignal; and modulating and outputting the complex signal; in a basestation, receiving the signal transmitted from the mobile station,demodulating the received signal in order to generate the complexsignal; and performing IQ separating of the complex signal in order tooutput the transmission data for the data channel and the control datafor the control channel, wherein in the mobile station, when controldata for an additional control channel are added, the control data forthe additional control channel are distributed on I axis and Q axis, andthe IQ multiplexing for the data is performed in order to generate thecomplex signal, and in the base station, the control data for theadditional control channel distributed on I axis and Q axis aresynthesized, and the synthesized one are output when the control datafor the additional control channel are distributed on I axis and Q axis.